Carriages were thrown off the tracks, some of them crushed and engulfed in flames, when a passenger train and one carrying freight collided on the same track at high speed in central Greece.
There were more than 350 people on board the passenger train, many of them university students going back to the northern town of Thessaloniki from the capital Athens after a long holiday weekend.
Anger has grown across the country over the crash, which the government has attributed to human error but which unions say was inevitable due to lack of maintenance and faulty signalling.
After evening protests in the past two days, some 2000 students took to the streets in Athens on Friday, blocking the road in front of parliament for a moment of silence.
Clashes broke out with some protesters who threw petrol bombs and set garbage bins on fire.
Police responded with volleys of tear gas.
Students also demonstrated in Larissa, the central city near where the crash took place.
Students held up black balloons.
One placard read: "It was not an accident, it was murder."
The word "murderers" was painted in red on the street.
"Most of all we feel rage that this could happen in the year 2023, how two trains can collide ... when there is so much technology," 21-year-old student Aggelos Thomopolous said.
Outside the hospital in Larissa, where many of the victims were taken, the parents of a 22-year-old man waited in anguish for confirmation of what had happened to their son.
"They killed him, that is what happened. They are murderers. All of them," Panos Routsi said.
On Friday, 38 passengers were still being treated in hospital, seven of them in intensive care.
Railway workers who began a strike on Thursday extended their walkout by another 48 hours on Friday.
In schoolyards in Athens, students used their bags to write the words "call me when you get there", a phrase that has become one of the protest slogans.
Protesters also wrote the slogan in candles outside parliament.
Larissa's 59-year-old station master was arrested and has admitted to some responsibility, his lawyer said, while stressing he was not the only one to blame.
"The federation has been sounding alarm bells for so many years but it has never been taken seriously," the main rail workers' union said, demanding a meeting with the new transport minister, appointed after the crash with a mandate to ensure such a tragedy can never happen again.
The union said it wanted a clear timetable for the implementation of safety protocols.
Before the crash, the government had said an election would be held in the spring, with media citing April 9 as the most likely date.
Political analysts say that plan might now be pushed back.
